Which of the following is the basic Crow’s Foot symbol for the cardinality…
2021
Which of the following is the basic Crow’s Foot symbol for the cardinality value one in an Entity–Relationship diagram?
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CONCEPT
Crow’s Foot notation separates cardinality from participation. A bar is the basic marker for a cardinality of one, a circle marks optional participation, and a fork marks many.
When two endpoint markers are paired, the inner marker gives the minimum participation and the outer marker gives the maximum cardinality. Thus a double bar is the stricter mandatory range 1..1, whereas a single bar by itself is the basic symbol for the cardinality one.
APPLICATION
Read each image according to the role of its visible markers:
Image composition | Marker reading | Meaning |
|---|---|---|
Circle + bar | Minimum zero; maximum one | Optional, at most one |
Single bar | Basic cardinality marker | One |
Bar + bar | Minimum one; maximum one | Mandatory one-and-only-one |
Bar + fork | Minimum one; maximum many | One or many |
CROSS-CHECK
The clarified stem asks for the basic marker for the cardinality value one, not for a paired participation range. The official DSSSB 2021 TGT Computer Science Shift 5 paper marks the single-bar image, and the paired images add minimum-participation information beyond that basic marker.
RESULT
Therefore, the single unpaired bar is the basic Crow’s Foot marker for the cardinality value one.